Twenty Eleven – How to Center Navigation Menu?

start by re-installing the original style.css of Twenty Eleven; https://themes.svn.www.ads-software.com/twentyeleven/1.7/style.css

then possibly have a look at https://www.ads-software.com/support/topic/twenty-eleven-how-to-center-navigiation-menu?replies=20

Thank you for your reply. This is what i did to try and get it centred but no luck.
I will try and retrace my steps and put the correct access code back (take it from the original css) and see where i go then.

I have put the menu back to horizontal but just need to centre it.

As i said i did try the steps at https://www.ads-software.com/support/topic/twenty-eleven-how-to-center-navigiation-menu?replies=20 but it didnt work for me.

If anyone can help i would be most grateful.